I know you already said you wouldn't mind talking to him "as long as you're not mean," but that isn't an unbreakable promise. He's taken your willingness to have an occasional phone call as a signal that everything will be OK and everything can go back to the way it was. This is how we get sucked back in.
Maybe the best thing is just to say, "I've given it some thought and I really don't think talking any more is a good idea. I sincerely wish you the best, but please don't contact me again." Period. You already believed you had broken up, but he hasn't accepted that fact. If you want OUT of this dance, YOU will have to be the one to do it.
I think way too often we keep waiting and waiting until the alcoholic gives us "permission" to leave (of course, then we start questioning why they aren't trying harder to hold onto us). All of which keeps us locked into these bad relationships that are going nowhere but downhill.